A US Airways, foreground, and an American Airlines plane are seen parked at the terminal at Washington's Ronald Reagan National Airport, Tuesday, Aug. 13, 2013. The Justice Department and a number of U.S. state attorneys general on Tuesday challenged a proposed $11 billion merger between US Airways Group Inc. and American Airlines' parent company, AMR Corp.(AP Photo/Susan Walsh) ORG XMIT: VASW104 Photo: Susan Walsh / AP